Pakistan authorities arrested 10 alleged human traffickers days after dozens of migrants drowned off the coast of Greece, officials said on Sunday.
Prime Minister Shehbaz Sharif also ordered an immediate crackdown on agents engaged in people smuggling, saying they would be "severely punished".
Every year, thousands of young Pakistanis embark on perilous journeys attempting to enter Europe illegally in search of a better life.
There were likely dozens of Pakistanis among those aboard the rusty trawler that sank off Greece's Peloponnese peninsula on Wednesday, killing at least 78 people with hundreds more missing.
Officials said nine people had been detained in Pakistan-administered Kashmir -- home to a majority of the victims -- and one in Gujrat, a city that has long served as a springboard for migrants.
"They are presently under investigation for their involvement in facilitating the entire process," said Chaudhary Shaukat, a local official from Pakistan-administered Kashmir.
In a joint statement, the International Organization for Migration and UN Refugee Agency said between 400 to 750 people were believed to be aboard the ferry.
On Saturday, Pakistan's ministry of foreign affairs said 12 nationals had survived, but they had no information on how many were aboard the boat.
An immigration official told AFP on condition of anonymity that the figure could surpass 200.
"The Prime Minister has given a firm directive to intensify efforts in combating individuals involved in the heinous crime of human trafficking," his office said in a statement.
A combination of political turmoil and an economy on the brink of collapse drives tens of thousands of Pakistanis to leave the country -- legally and illegally.
Young men, primarily from eastern Punjab and northwestern Khyber Pakhtunkhwa province, often use a route through Iran, Libya, Turkey and Greece to unlawfully enter Europe.